Mutating
by I. H. Scribe
Summary: Kirk's summoned to the Med Bay, only to discover that McCoy is dying.


Fandoms: Thor, Star Trek 2009, Doom

Characters: Thor, Loki, Jim Kirk, Leonard McCoy (John Grimm)

Prompt: Magic doesn't exist, it's advanced technology to Spock, McCoy, Kirk. Star Trek technology is magic to the Asgardians. _and_ McCoy is Reaper and the C24 is mutating.

Prompt Made By: Quaff

Disclaimer: I don't own the following series(es) or any character(s) that follow, and unless _I. H. Scribe_ is listed after _Prompt Made By_ chances are I don't own the idea for this story either.

Notes: There ended up not being much Spock time, sorry.

* * *

><p>Kirk entered Med Bay, spotting McCoy on a bed, surrounded by the rest of the medical personnel, while two security officers stood over a woman Kirk barely recognized as one of the engineers Scotty was always complaining about.<p>

"Bones, what's goin' on?"

McCoy hissed in pain before answering, "It's a long, complicated story. The short version is I have a genetic enhancement and she just tried to kill me by mutating it."

"Tried?" the woman on the floor said. "The UAC's been working on that for years. You'll be dead by the end of the week."

"The UAC?" Kirk asked.

"The Union Aerospace Corporation," McCoy answered. "It split into two factions at the end of its stretch. The decent faction became the precursor for The United Federation of Planets. The other faction became a terrorist faction that kept its original name." McCoy grunted in pain. "And if they did what I think they did."

"Doctor McCoy!" one of the nurses ran into the room. She handed him a device Kirk had never seen before, that McCoy used to test his blood.

"What is that?" Kirk asked.

"Thanks Chapel," McCoy said. "It's to help me keep track of something that's been in my blood for a while." The device beeped, and whatever it told McCoy, he wasn't happy about. He leveled a death glare more terrifying than any Kirk had ever seen before at the woman on the floor. "You _idiots_!"

"What, Bones?" Kirk said.

"Good news, I'm not gonna die. Bad news, I'll start trying to kill everyone within the week if I don't find a way to fix this."

"You can fix it, right?"

For the first time since Kirk met him, McCoy seemed unsure. "I've never worked with C24 before. Even with Sam's notes, whatever the UAC did to it took years. I only have a week."

"Can you do it?"

"Not without help. Jim, I need you to send a message for me."

* * *

><p>Kirk didn't know what the message was – it was in a language no one on the ship, even Uhura, recognized – but he trusted Bones with his life, and the lives of his crew, so on the message went into unexplored space.<p>

Four hours later came the reply in the form of a large ship suddenly appearing in front of the Enterprise, which hadn't moved since McCoy had been attacked. _The Avenger _was painted in bold letters across the side and front hulls of the ship.

"They're hailing us."

"Put it onscreen."

A muscled woman with dark hair came onto the screen, asking one question, "Where is John Grimm?"

Kirk blinked. "Who?"

* * *

><p>John Grimm, as it turned out, was the name McCoy had been born as.<p>

"We're going to have a long talk about keeping things you shouldn't from your Captain," Kirk grumbled, after McCoy greeted the woman, Sif.

"Let's get me through this alive first."

"What happened?" Sif asked. McCoy, in between grunts and hisses of pain, explained what had happened with the engineering woman. Sif already appeared to know what C24 was.

"Now the C24 is mutating."

"Mutating how?"

"As in going the other way," McCoy said, handing her the device he used earlier.

"Thor will never allow you to turn," Sif said. Kirk didn't like how that sounded like a threat, but McCoy relaxed when he heard it.

"Where is Thor anyway? Isn't he usually the Captain of the Avenger?"

"He's tracking down Loki. Loki has studied the C24 for longer than anyone else. If anyone can help you, it will be him."

"Let's hope so. I don't fancy finding out what type of monster I'd be."

* * *

><p>Sif returned to the Avenger, promising to contact them when Thor contacted her. Kirk finally managed to corner McCoy, who had decided to keep working, and pulled him into McCoy's office, before forcing him to sit on the old, beat-up couch the man had there (much more comfortable than the desk chair).<p>

"Explain. Now." McCoy glared at him, and Kirk glared right back.

Finally McCoy sighed, "Back then, when I was John Grimm, I had a twin sister, Sam. We had a huge fight when we were younger, so when my team got sent to Olduvai, where she was a scientist, I almost didn't go. It's a good thing I ended up going after all.

"They were studying something called C24 there. We didn't find out until it was too late that the C24 effected people differently. Some people it turned into monsters. _Most_ people it turned into monsters. But a few, a very, very few, it gave them enhanced senses and strength."

"That's what it gave you."

"Yeah. Of the other members of my team, only Kid would've been like me, and Sarge killed him. Sarge became this huge hulking beast. The only way to save myself and my sister was to use the C24. Sam was so sure that I wouldn't be like him, and she was right.

"I fought off Sarge, and got us out of there, but by that time we were the only survivors. The UAC chased us for a while, until the Asgardians came. C24 was apparently a man-made invention, an attempt to turn a human into an Asgardian with all the strength, longevity, and senses of one. It didn't quite work out, since I was still human, but I got everything else that came with being an Asgardian.

"The Asgardians forced UAC to back down. Most did, those are the ones that became the precursor to the Federation, but some didn't."

"The terrorists, like Kale."

"Kale? Is that her name?" McCoy mused. "Whatever they did to the C24, it's mutating. It's changing me into one of those monsters, but instead of the usual quick change, it's going slowly."

"Slow enough for us to stop it."

"Slow enough for you to stop _me_ if necessary."

"Bones, I won't-!"

"Shut up. I refuse to become one of those monsters. I'm not asking you to kill me, but don't you dare stop Thor when he does."

"It won't come to that. We'll find a way to fix you."

"I hope you're right."

"Is that why you called the Asgardians again? They've dealt with this before?"

"Oh, hell no. The Asgardians wanted to kill me, even after forcing the UAC to back off. It wasn't until years later that I ended up saving Thor's life in battle. He's the crown prince of Asgard. In return for saving his life, he told 'em to leave me alone to live my life. I've been Leonard McCoy ever since. I'll owe him a favor for this."

* * *

><p>It took two days for Sif to send word that Thor had found Loki and would be with them shortly. Two long days in which McCoy deteriorated quickly, and ended up locking himself in the brig.<p>

"It might be the only thing that holds me," he had said when Spock asked. Spock nodded.

"We will find a way to save you, Doctor."

"Yeah, well, if we don't," McCoy started. He growled in pain and continued, "If we don't, make sure Jim doesn't interfere when Thor, well..."

"That will not be necessary," was all Spock would say.

* * *

><p>Kirk's first impression of Thor and Loki was a father exasperated with his misbehaving five-year-old son.<p>

Loki's muttering of, "Interfering older brothers that need a good kick up the rear," corrected him.

Loki took the device, multiple samples of McCoy's blood and saliva, and Sam's notes, and locked himself in a lab. Thor paced outside it for a while, until Loki poked his head out, yelled at him for disturbing him, and chased him off.

* * *

><p>"Hello Thor," McCoy said.<p>

"John Grimm, it is good to see you alive again."

"Didn't Sif tell you? It's Leonard McCoy now."

"Wouldn't you feel more comfortable outside that prison cell?"

"Not until you're brother tells me if he can fix me or not. I will not harm any of the people on this ship."

"Don't worry. I won't let you."

* * *

><p>The next three days, no one saw hide or hair of Loki, as he remained locked in the lab. McCoy, at least, had been convinced to come out of the brig, though he didn't let Thor out of his sight, and he kept as large a space as he could between himself and the rest of the Enterprise crew.<p>

Finally, Loki emerged, looking half-crazed and starved. He informed McCoy of his findings in the cafeteria, while scarfing down anything placed in front of him.

"There isn't a cure for the mutation that's happening," Loki said. Kirk and Spock tensed, but McCoy just seemed resigned to his fate. At least until Loki rolled his eyes and kicked him underneath the table. "Are all you mortals this damn moody? I can't cure it but I can remove it."

"The mutation?" Kirk asked.

"The C24."

"All of it?" McCoy asked.

"No more enhanced senses, no more super strength, no more century upon century of life, just plain old human John Grimm."

"Leonard McCoy," he corrected, stunned. "I'll be normal again?"

"Yes."

"I won't outlive my daughter," McCoy whispered. That was the reason he hadn't fought as hard as he could have for custody of her. To outlive her was always going to have hurt, but to do so after raising her by himself? That would have been even worse.

"I'll need to check her, of course, to see if any of the C24 managed to pass on, but no, you won't outlive her anymore."

"Do it."

* * *

><p>It took Loki twelve hours to remove all of the C24, and McCoy came out of the room looking as though he'd aged nearly a decade.<p>

"Everything alright?" Kirk asked.

"Just fine," McCoy said. "Now, let me talk to Ms. Kale. She and I need to have a talk about not messing with things you don't understand."

Kirk grinned. Kale was in for hell now. Bones' lectures were terrifying.

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><p>As always, I am accepting prompts, however, I am not accepting prompts through reviews. If you wish to give me a prompt, please see the Accepting Prompts section of my profile for instructions. Thank you.<p>

I. H. Scribe


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